Light controlled signal system



Sept. 21, 1965 R. F. BEGUIN LIGHT CONTROLLED SIGNAL SYSTEM 5 Cmw i wm e3 +1 05N wfi 3 M 12 L e W M urL 1 w? 4 Z Filed March 8, 1963 UnitedStates Patent 3,207,948 LIGHT CONTROLLED SIGNAL SYSTEM Richard F.Beguin, Evanston, 11]., assignor, by mesne assignments, to Fidelitone,Inc., Chicago, 111., a corporation of Illinois Filed Mar. 8, 1963, Ser.No. 263,884 2 Claims. (Cl. 315-459) This invention relates to a lightcontrolled signal system and more particularly to a light controlledassembly for use in railroad work. Signal lamps for use on railroadtrack switches and cross-overs have been used for many years. Suchsignal lamps may be tied in with track switching mechanism or trackcontrol system for showing a clear track or a stop. Such signal lampshave generally been kerosene lamps wherein four lenses or bulls eyesfacing in four directions have been provided. Such lamps burncontinuously on one filling of kerosene for about a week. Thereafter,the wick must be trimmed, the lenses cleaned and a charge of kerosenemust be provided. This upkeep is quite costly.

By contrast, a signal lamp operated from a primary battery can, underproper conditions, energize a signal lamp for longer periods of time andrequires battery replacement only, thus reducing the cost of upkeep.This invention provides an electrically energized lamp system which canbe used as a replacement of an entire kerosene burner assembly, with thekerosene tank part being used as a housing. In accordance with thepresent invention, means are provided for energizing the signal lamponly during the time when there is little or no daylight. The lamp whenthus energized may in one form of the invention be on continuously or,in another form of the invention, may flash intermittently.

A system embodying the present invention is efficient from an electricalpoint of view in reducing current drain to a minimum. Furthermore,during the time that the signal lamp is energized, the new systempermits most of the power used by the entire system to be fed to thesignal lamp, with minimum power used in the control system. Theinvention provides for eflicient operation of the control system andquick transition from On to OE of the signal lamp.

A further feature of the system embodying the present invention residesin the mechanical structure of the assembly. This mechanical structuremakes it impossible to dispose the assembly incorrectly in the holder.This is quite important, since incorrect disposition of the componentsof the system may interfere with the full passage of light from thesignal lamp through the lenses or bulls eyes of the housing. Inaddition, the physical layout of the system embodying the presentinvention makes it impossible for faulty operation due to obstructionsin the light path between the lenses on the one hand and the signal lampbulb on the other hand, and also between the lenses on the one hand andthe light responsive element on the other hand.

In general, the physical layout of the parts is such that not only isthe entire assembly positioned in the lamp housing properly with respectto the bulls eyes, but no part of the assembly is likely to cast anyshadows in the bulls eye when the signal lamp is lit.

For a fuller understanding of the invention, reference will now be madeto the drawings wherein:

FIGURE 1 is an elevation of a lamp embodying the invention, one partbeing broken away.

FIGURE 2 is a section on broken line 2-2 of FIG- URE 3.

FIGURE 3 is a section on line 33 of FIGURE 1.

Referring first to FIGURE 4, indicates a photo-electric cell of the typeadapted to generate a potential. Such 3,207,948 Patented Sept. 21, 1965cells are used in photo-meters for photography and the like. Cell 10 hascathode 11 connected to base 12b of PNP transistor 12. Transistor 12 hasemitter 12e connected by wire 13 to junction point 14 on wire 15 goingto anode 16 of cell 10.

Wire 15 has junction point 18 connected by wire 19 to base 201) of NPNtransistor 20, emitter 20a of this transistor being connected by wire 21to junction point 22 on wire 23 which is connected to collector oftransistor 12.

From junction point 18, a connection including bias resistor 25 isprovided to junction point 26 which is connected to the positiveterminal of an energizing battery. Junction point 26 is connected toemitter 28a of PNP transistor 28 whose base 28b is connected throughbias resistor 30 back to junction point 26 and thus to emitter 28e. Base28b of transistor 28 is also connected through coupling resistor 33 tocollector electrode 200 of transistor 28. Base 20b of transistor 20 isconnected by wire 35 through capacitor 36 and dropping resistor 37through junction point 38 to collector electrode 280 of transistor 28.Junction point 38 is connected to one terminal of incandescent lamp 40,the other terminal of which is connected to wire 23 which is connectedto the negative terminal of the energizing battery.

The circuit described and including capacitor 36 is adapted to flash theincandescent lamp intermittently, providing photo-electric cell 10 isnot exposed to light. Without capacitor 36, the lamp will be energizedcontinuously rather than flashed, under the same conditions.

Assuming that the resistors are of proper value, and assuming capacitor36 is shorted out, the system works as follows. As long as cell 10 hasno light thereon to generate a potential, emitter 12e will be biasedpositively to base 12b and transistor 12 will be non-conductive. Whiletransistor 12 does not conduct, the potential of its collector andemitter electrodes will not be impressed upon the emitter and baseelectrodes of NPN transistor 20 and transistor 20 conducts. When cell 10first has light from outside cut off (as when night falls) transistor 12becomes non-conductive and transistor 28 starts to conduct. The relativeelectrode potentials of transistor 20 are impressed upon PNP transistor28 and causes normally non conducting transistor 28 to become slightlyconductive. The changing electrode potentials at transistor 28 reactsupon transistor 20 and its electrodes so that one reacts upon the othertransistor to effect a quick change of the two transistors fromnon-conducting to conducting. As soon as transistor 28 conducts fully,current through incandescent bulb 40 will flow and the bulb will beenergized.

Transistor 2% draws little current, since the current must go throughresistor 37 which is normally quite high in value. If flashing isdesired, capacitor 33 is in circuit as shown. When lamp 40 is on, thedrop between junctions 38 and 26 causes capacitor 36 to charge. Whencapacitor 36 is charged, transistor 20 cuts oil and this cuts transistor28 01f. As soon as both transistors cut off, capacitor 36 discharges.Then transistors 20* and 28 assume their normal conducting condition inthe manner set forth when cell 10 first initiates the operation. Whenthis occurs, current will flow through capacitor 36 to charge the sameand during this time, incandescent bulb 40 will be energized. When lamp40 is on, most of the IR drop between point 26 and wire 23 is across thelamp. This provides high efiiciency.

When light is falling upon cell 10, a potential is generated by the celland the base of transistor 12 is no longer negative to the emitter andcauses transistor 12 to conduct. This in turn causes transistor 20 tobegin to cut off and this reacts upon transistor 28 and vice versa. Theswitching action initiated by cell results in very fast action by thetransistors. In addition, the flashing action due to capacitor 36results in fast switching of lamp 40. In all cases, when lamp 40 isbeing extinguished, whether by the action of cell 10 or capacitor 36,the reduction in current through the lamp is fast.

As examples, the components making up a system without capacitor 36 canhave the following values.

Cell 10 is a silicon solar cell SS22LC sold by Solar System, Inc.Transistsor 12 is a GT2823. Transistor is a GT1938, and transistor 28 isa GT2823.

Resistor has a value of 22,000 ohms; resistor 30 has a value of 330ohms; resistor 33 has a value of 330 ohms; and resistor 37 has a valueof 27,000 ohms. A 6- volt battery is used for energizing the system andthe bulb is a type 1867 bulb of General Electric Company.

If flashing of bulb 40 is desired, then capacitor 36 is used, and, in anexample, this can be a 20 microfarad capacitor. Resistor 37 will be 3300ohms, while resistor will be 100,000 ohms. Resistor 30 will be 1800ohms. Everything else will be the same.

The entire system has the advantage of not relying upon resistors inhigh megohm ranges. Such high resistors cause considerable ditficultydue to the possibility of moisture or dirt forming a conducting or highresistance film between parts and impairing the operation of the system.All the components are disposed in metal can 50, which is attached tobracket 51 of canister 52. Canister 52 has a battery in the interiorthereof and access to the battery may be obtained by opening canistertop 54 to expose the battery.

Bracket 51 is a strip of metal having top portion 56 on which can 50 issupported by spring clips 57. Bracket 51 has side arms 58 and 59 whichextend toward canister top 54 and welded thereto. Supported from topportion 56 is lamp socket 61 carrying lamp 40. Lamp extends straightdown and the axis of the lamp and socket is substantially midway betweenarms 58 and 59. Canister top 52 carries bracket 63 upon which issupported 'photo-cell housing 64 having the cell proper 10 and window 65through which light can reach cell 10. Cell housing 64 is positionedbelow lamp 40 and offset along the direction of portion 56 of bracket51. Cell window 65 is directed at to the length of portion 56 andparallel to the plane of cover 52. Bracket 51 is narrow enough so thatwindow 65 and lamp 40 will have a light path in the direction faced bywindow 65. The entire assembly of light and cell carried by cover 52fits inside of housing cover 68 of square shape as viewed in plan. Thuscover 68 has four side walls carrying four lenses or bulls-eyes 69 to 72inclusive. These may be of glass or plastic, of suitable colors andsupported in conventional fashion. The diameter of each lens and theelevation is such that when housing top 68 is positioned over lamp base74, light from bulb 40 can go through all lenses in four directions.Cell window 64 is below lamp 40 but can receive suflicient light throughlens 69 to be controlled by light external to the entire lamp housing.Lens 69 has its surfaces so arranged that at night when lamp 40 is lit,there will be little or no light from lamp 40 to affect cell 10, as theresult of reflection. Furthermore, cell housing 64 is close enough tolamp 40 so no shadow of housing 64 will appear in the beam from lens 69due to light originating with lamp 40.

The entire lantern can be handled by grip 76. Lamp base 74 may fit or beshaped to be attached to any suit- 4 able support. Base 74 is simplypart of the old kerosene lamp which is modernized by the presentinvention.

The length of portion 56 of assembly bracket 51 is such that theassembly and lamp housing 68 can be put together only as illustrated inFIGURE 2, where bracket portion 56 is diagonally disposed in housing 68.

Resistor 25 and capacitor 36 control the flash repetition rate.Capacitor 36 and resistor 37 determine the On time. Resistor 33 limitsthe current and is determined by the transistor characteristics.Resistor 30 holds transistor 28 at cut-oflf and prevents excessiveleakage at warm temperatures. In cold weather, this resistor can be leftout. Resistor 30 and lamp 40 will both affect the timing.

What is claimed is:

1. A lamp system for use where a lamp must be flashed intermittentlyunder conditions of darkness and cut off under conditions of daylight,said system comprising a photo-electric cell having a cathode and ananode and adapted to generate a potential under the influence of light,a first transistor of the PNP type having a base, collector and emitterelectrode respectively, means for connecting the cathode to said base,means for connecting the anode to said emitter, a second transistor ofthe NPN type, a direct connection between the emitter of the firsttransistor and the base of the second transistor, a direct connectionbetween the collector of the first transistor and the emitter of thesecond transistor, a first, resistor disposed between the base of saidsecond transistor and the emitter of a third PNP transistor, a secondresistor disposed between the collector of the second transistor and thebase of the third transistor, a third resistor connected across the baseand emitter of the third transistor, an incandescent lamp connectedbetween the collector of the third transistor and the emitter of thesecond transistor, and a circuit between the base of the secondtransistor and the collector of the third transistor, said last namedcircuit including a fourth resistor, said system be ing adapted to havea battery whose positive terminal is connected to the emitter of thethird transistor and whose negative terminal is connected to the emitterof the second trnasistor, the value of said first resistor being greaterthan the second resistor, said second and third resistors havinggenerally values of the same order, said fourth resistor having a valuewhich is between that of the first resistor and the values of the secondand third resistors, said system being adapted to switch said light onor olf quickly as the result of action on the photo-cell, the second andthird transistors cooperating with each other to effect a quick changein the conductive or nonconductive conditions, both of said transistorsbeing substantially conductive or non-conductive simultaneously.

2. The system according to claim 1 wherein said last named circuit has acapacitor connected between the collector of the third transistor andthe base of the second transistor, said capacitor being in series withthe fourth resistor and functioning to cause said signal lamp to flashintermittently when the photo-cell is dark.

References Cited by the Examiner UNITED STATES PATENTS 2,973,456 2/61Smyth 3l5l59 3,093,744 6/ 63 Tabet 250-239 3,128,412 4/64 Abromaitis315159 JOHN W. HUCKERT, Primary Examiner. ARTHUR GAUSS, Examiner.

1. A LAMP SYSTEM FOR USE WHERE A LAMP MUST BE FLASHED INTERMITTENTLYUNDER CONDITIONS OF DARKNESS AND CUT OFF UNDER CONDITIONS OF DAYLIGHT,SAID SYSTEM COMPRISING A PHOTO-ELECTRIC CELL HAVING A CATHODE AND AANODE AND ADAPTED TO GENERRATE A POTENTIAL UNEDER THE IMFLUENCE OFLIGHT, A FIRST TRANSISTOR OF THE PNP TYPE HAVING A BASE, COLLECTOR ANDEMITTER ELECTRODE RESPECTIVELY, MEANS FOR CONNECTING THE CATHODE TO SAIDBASE, MEANS FOR CONNECTING THE ANODE TO SAID EMITTER, A SECONDTRANSISTOR OF THE NPN TYPE, A DIRECT CONNECTION BETWEEN THE EMITTER OFTHE FIRST TRANSISTOR AND THE BASE OF THE SECOND TRANSISTOR, A DIRECTCONNECTION BETWEEN THE COLLECTOR OF THE FIRST TRANSISTOR AND THE EMITTEROF THE SECOND TRANSISTOR, A FIRST RESISTOR DISPOSED BETWEEN THE BASE OFSAID SECOND TRANSISTOR AND THE EMITTER OF A THIRD PNP TRANSISTOR, ASECOND RESISTOR DISPOSED BETWEEN THE COLLECTOR OF THE SECOND TRANSISTORAND THE BASE OF THE THIRD TRANSISTOR, A THIRD RESISTOR CONNECTED ACROSSTHE BASE AND EMITTER OF THE THIRD TRANSISTOR, AN INCANDESCENT LAMPCONNECTED BETWEEN THE COLLECTOR OF THE THIRD TRANSISTOR AND THE EMITTEROF THE SECOND TRANSISTOR, AND A CIRCUIT BETWEEN THE BASE OF THE SECONDTRANSISTOR AND THE COLLECTOR OF THE THIRD TRANSISTOR, SAID LAST NAMEDCIRCUIT INCLUDING A FOURTH RESISTOR, SAID SYSTEM BEING ADAPTED TO HAVE ABATTERY WHOSE POSITIVE TERMINAL IS CONNECTED TO THE EMITTER OF THE THIRDTRANSISTOR AND WHOSE NEGATIVE TERMINAL IS CONNECTED TO THE EMITTER OFTHE SECOND TRANSISTOR, THE VALUE OF SAID FIRST RESISTOR BEING GREATERTHAN THE SECOND RESISTOR, SAID SECOND AND THIRD RESISTORS HAVINGGENERALLY VALUES OF THE SAME ORDER, SAID FOURTH RESISTOR HAVING A VALUEWHICH IS BETWEEN THAT OF THE FIRST RESISTOR AND THE VALUES OF THE SECONDAND THIRD RESISTORS, SAID SYSTEM BEING ADAPTED TO SWITCH SAID LIGHT ONOR OFF QUICKLY AS THE RESULT OF ACTION ON THE PHOTO-CELL THE SECOND ANDTHIRD TRANSISTORS COOPERATING WITH EACH OTHER TO EFFECT A QUICK CHANGEIN THE CONDUCTIVE OR NONCONDUCTIVE CONDITIONS, BOTH OF SAID TRANSISTORSBEING SUBSTANTIALLY CONDUCTIVE OR NON-CONDUCTIVE SIMULTANEOUSLY.